[Bug target/111037] New: RISC-V: Invalid vsetvli fusion

[kito at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111037

            Bug ID: 111037
           Summary: RISC-V: Invalid vsetvli fusion
           Product: gcc
           Version: 14.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: target
          Assignee: unassigned at gcc dot gnu.org
          Reporter: kito at gcc dot gnu.org
                CC: juzhe.zhong at rivai dot ai
  Target Milestone: ---
            Target: riscv64

Reduced case:
```
#include <riscv_vector.h>

void foo(_Float16 y, int64_t *i64p)
{
  vint64m1_t vx =__riscv_vle64_v_i64m1 (i64p, 1);
  vx = __riscv_vadd_vv_i64m1 (vx, vx, 1);
  vfloat16m1_t vy =__riscv_vfmv_s_f_f16m1 (y, 1);
  asm volatile ("# use %0 %1" : : "vr"(vx), "vr" (vy));
}
```

Command to reproduce:
$ riscv64-unknown-elf-gcc -O3 -march=rv64gczve64f_zvfh

foo:
        vsetivli        zero,1,e64,m1,ta,ma
        vle64.v v1,0(a0)
        vfmv.s.f        v2,fa0 # Will raise illegal instruction here, because
we don't have F64 for vector 
        vadd.vv v1,v1,v1
        ret